#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <vector>

using namespace std;

struct ListNode {
    int val;
    ListNode* next;
    ListNode(int x) : val(x), next(NULL) {}
};

struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class CQueue {
   private:
    vector<int> queue;
    int head = 0, tail = 0;

   public:
    CQueue() {}

    void appendTail(int value) {
        queue.push_back(value);
        tail++;
    }

    int deleteHead() {
        if (head >= tail)
            return -1;
        return queue[head++];
    }
};

int main() {
    cout << "Hello, World!";
    return 0;
}